1. Field of the Invention
The present invention relates to a charging apparatus that can prevent overcharging of a secondary battery.
2. Description of the Related Art
A so-called secondary battery (also referred to as a storage battery, accumulator or rechargeable battery) that is repeatedly usable as a battery by being charged again and again is known in the art. When charging the secondary battery, measures to deal with overcharging of the secondary battery are taken to prevent breakdown or damage of the secondary battery. For example, Japanese Patent Application Publication (Kokai) No. 9-261861 discloses an apparatus for such purpose. When a voltage across a secondary battery becomes higher than or equal to a predetermined value, an N-channel power metal oxide semiconductor field effect transistor (MOSFET) connected in parallel to a solar cell is turned on to interrupt charging current from the solar cell to the battery, thereby preventing overcharging of the secondary battery.